1. Field of the Invention
This invention relates to a camera having a viewfinder optical system.
2. Description of the Related Art
The number of cameras of the kind using a hollow roof mirror formed by combining mirrors for a viewfinder optical system in place of a roof prism made of glass has recently increased for reduction in cost and weight.
Cameras are generally arranged these days, on the other hand, to have an electronic circuit on a large scale. The electronic circuit is installed on a flexible printed circuit board. The flexible printed circuit board is laid by drawing it around in a complex shape in a narrow space available within the camera. In the case of the camera of the kind mentioned above, a space available between the roof surface of the hollow roof mirror and the upper cover of the camera is used in fitting the electronic circuit.
The hollow roof mirror is a very delicate high-precision part. Even a slight amount of external pressure onto the hollow roof mirror would deform the hollow roof mirror, thereby bringing about an adverse effect on an image appearing in the viewfinder. If the flexible printed circuit board is mounted directly on the hollow roof mirror, the roof surface of the hollow roof mirror would be pressed by the tension of the flexible printed circuit board, so that the hollow roof mirror would be warped. Under such a condition, the viewfinder image would be distorted by the warp of the hollow roof mirror. The flexible printed circuit board must be arranged not to push the hollow roof mirror.
FIG. 5 shows the installing structure of the conventional camera having a hollow roof mirror. Referring to FIG. 5, reference numeral 2 denotes a flexible printed circuit board. Electronic parts (not shown) which constitute an electronic circuit for the camera are installed on the flexible printed circuit board 2. The camera is provided with an upper cover 3 and a mirror box 4. The mirror box 4 supports a mirror (not shown) which is arranged to be movable between a position where a shot can be taken (hereinafter referred to as a shooting position) and another position where a sight of an image can be taken through the viewfinder (hereinafter referred to as a viewfinder image sighting position). A hollow roof mirror 1 which constitutes a viewfinder optical system is disposed in a predetermined position on the mirror box 4. The hollow roof mirror 1 has roof surfaces 1a and 1b of a roof shape. A protection cover 5 which is made of a metal plate is disposed above the roof surfaces 1a and 1b of the hollow roof mirror 1 to protect the hollow roof mirror 1 with an adequate clearance left between the protection cover 5 and the roof surfaces 1a and 1b. The flexible printed circuit board 2 is disposed above the protection cover 5. The flexible printed circuit board 2 is thus prevented from coming into direct contact with the hollow roof mirror 1, so that the hollow roof mirror 1 can be prevented from being deformed by the tension of the flexible printed circuit board 2.
The above-stated arrangement of the conventional camera, however, necessitates use of an additional dedicated part (i.e., the protection cover 5) of a size large enough to cover the whole roof surfaces 1a and 1b as to protect the hollow roof mirror 1. The use of this part causes an increase in cost.
Further, the protection cover 5 is arranged to leave a certain amount of clearance between the inner side of the protection cover 5 and the hollow roof mirror 1, the flexible printed circuit board 2 is installed above the protection cover 5, and the upper cover 3 of the camera is disposed above the flexible printed circuit board 2. This arrangement causes an increase in size of the camera and thus presents another shortcoming of the conventional camera.